1. Field of the Invention
The present invention relates to a method and apparatus for abatement of effluent from any CVD process using a metal source reagent liquid solution comprising at least one metal coordination complex including a metal to which is coordinatively bound at least one ligand in a stable complex and a solvent for that metal coordination complex e.g., abatement of effluent from a multi-component metal oxide chemical vapor deposition (CVD) process used for forming barium strontium titanate (BST) thin films on substrates.
2. Description of the Related Art
BST is an important material in the semiconductor manufacturing industry for fabrication of thin film dielectric microelectronic devices. Such fabrication typically is carried out by chemical vapor deposition (CVD), in which precursors (source reagents) for the respective barium, strontium and titanium components of the product film are volatilized for use in the deposition process.
The source reagents for the BST film formation process may be provided to the CVD reactor by a liquid delivery process, in which the metalorganic precursors for the barium, strontium and titanium components are dissolved in a suitable solvent medium such as n-butyl acetate or tetrahydrofuran. The liquid solution containing precursors and corresponding solvent (separate solutions of different precursors can also be used) is pumped into a vaporizer comprising a hot zone maintained at low pressure. In the vaporizer, the liquid solution is vaporized at high rate (xe2x80x9cflash vaporizedxe2x80x9d) under controlled temperature, pressure, and flow conditions. The vaporizer is advantageously flushed with solvent immediately before and after deposition to prevent accumulation of solid species that could cause clogging in the process equipment and associated piping, valves and fittings.
In the vaporizer, or downstream therefrom, the precursor vapor is combined with a carrier gas (e.g., argon or nitrogen) and an oxidizer (e.g., oxygen or nitrous oxide). The combined precursor vapor mixture then is flowed to the CVD deposition chamber.
The CVD deposition chamber is typically operated at low pressure, e.g., on the order of 100 millitorr, by deployment of a dry pump or wet pump on the discharge of the system. In such chamber, the precursors are decomposed on the heated substrate by a thermal reaction of the combined gases, organic vapors, and metalorganic precursors, resulting in the deposition of a thin perovskite film of BST material on the wafer substrate. After chemical deposition, the wafer coated with the BST film is transferred to a separate chamber for annealing.
The effluent from the CVD deposition chamber in the CVD BST process comprises organic species, metals, unreacted precursor, precursor decomposition species and other thermal reaction products deriving from the CVD operation.
Currently, there is no effective abatement scheme commercially available for the effluent of such CVD BST process.
The foregoing issues are not unique to the CVD BST process. They also apply to other multi-component metal oxides deposited by CVD processes using metal source reagent liquid solutions which comprise at least one metal coordination complex including a metal to which is coordinatively bound at least one ligand in a stable complex and a suitable solvent medium for that metal coordination complex. These include the multi-component metal oxide CVD processes using ligand exchange resistant metal-organic precursor solutions described in U.S. Pat. No. 5,820,664 issued Oct. 13, 1998 to Gardiner et al. and assigned to Advanced Technology Materials, Inc., Danbury, Conn.
The present invention relates to abatement of effluent produced by multi-component metal oxides deposited by CVD processes using metal source reagent liquid solutions which comprise at least one metal coordination complex including a metal to which is coordinatively bound at least one ligand in a stable complex and a suitable solvent medium for that metal coordination complex e.g., CVD of BST.
In one aspect, the invention relates to a method for abatement of effluent from a CVD process for depositing a multi-component metal oxide film on a substrate, in which the effluent is flowed through a sorbent bed having sorptive affinity for contaminant species (precursor species and CVD process by-products) in the effluent.
In a specific embodiment, effluent from the CVD process is flowed in sequence through a metals trap, a motive fluid driver, and a sorbent bed having sorptive affinity for contaminant species in the effluent.
The method may further comprise monitoring the effluent discharged from the sorbent bed, to detect breakthrough of a selected contaminant component.
The invention relates in another aspect to an apparatus for abatement of effluent from a CVD process for depositing multi-component metal oxide on a substrate from a precursor composition, wherein the apparatus comprises a sorbent bed having sorptive affinity for contaminants in the effluent. Such sorbent bed may be part of an effluent flow circuit including a metals trap, a motive fluid driver, and a sorbent bed having sorptive affinity for contaminants in the effluent, optionally equipped with an endpoint detector for detecting the endpoint of sorption of the sorbent bed.
The apparatus described above may further include a semiconductor manufacturing facility whose operation comprises the CVD process.
Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.